Apparatus for contacting a free-flowing particulate solid with a fluid

ABSTRACT

Coffee, cocoa, malt, and other free-flowing, granular solid materials may be roasted in a stream of hot air in a drum rotating about its horizontal axis and axially divided into compartments by annular, radial partitions. The compartments are connected in axial sequence by channels outside the drum cavity which communicate with the compartments through apertures in the circumference of the drum. The solid material is fed to the axially first compartment and discharged from the axially last compartment, the dwell time in each compartment being determined by the spacing of the partitions and the effective flow sections of the channels. Hot air is blown into each compartment from nozzles mounted on a stationary support centered in the drum, the discharge orifices of the nozzles being submersed in the granular material.

July 3, 1973 United States Patent [191 Von Gimborn APPARATUS FOR CONTACTING A FREE-FLOWING PARTICULATE SOLID WITH A FLUID.

, Primary Examiner-Carroll B. Dority, Jr. Carl Hans von Gimborn, Emmerich Assistant Examiner-Larry I. Schwartz Germany Attorney-Kurt Kelman et al.

[75] Inventor:

[57] ABSTRACT Coffee, cocoa, malt, and other free-flowing, granular [73] Assignee: Probat-Werke von Gimborn & Co.

KG, Emmerich, Germany Dec. 28, 1971 [22] Filed:

[2i] Appl. No.: 213,107

solid materials may be roasted in a stream of hot air in a drum rotating about its horizontal axis and axially divided into compartments by annular, radial partitions. The compartments are connected in axial sequence by Foreign Application Priority Data I channels outside the drum cavity which communicate Jan. 5, 1971 Germany................... P 21 00 248.2

with the compartments through apertures in the circumference of the drum. The solid material is fed to the 34/109 6 a i3 axially first compartment and discharged from the axi- 109 136 ally last compartment, the dwell time in each compart- [58] Field of Search......................

ment being determined by the spacing of the partitions and the effective flow sections of the channels. Hot air is blown into each compartment from nozzles mounted on a stationary support centered in the drum, the dis- [56] References Cited UNITED STATES PATENTS charge orifices of the nozzles being submersed in the granular material.

C u t a S mm C APPARATUS FOR CONTACTING A FREE-FLOWING PARTICULAT'E SOLID WITH A FLUID This invention relates to the treatment of freeflowing, granular solids, and particularly to apparatus for contacting such solids with a fluid, more specifically a gas.

The invention has been found particularly advantageous in the roasting of coffee and like materials, and will be described hereinafter with reference to an embodiment suitable for this purpose, but it will be under stood that the invention is not limited to this application.

In its more specific aspects, the invention is concerned with an improvement in driers, ovens, and like devices in which a granular solid material is contacted with a fluid, particularly a gas, in a rotating drum through which the treated material travels in an axial direction while'exposed to the fluid.

It is difficult to achieve uniform exposure of the granular material to the fluid in known devices which are simple in their structure and can be constructed and operated at low cost, and devices providing adequately uniform treatment are complex and costly.

A primary object of the invention is the provision of a drum-type apparatus of the type referred to which reliably and uniformly mixes granular material while being exposed to a fluid, and thus ensures uniform treatment of the solid material.

Another object is the provision of such apparatus which is simple in its structure, and can be built and perated at low cost.

With these objects in view, the invention provides a drum having a horizontally extending axis and enclosing a cavity. The drum is rotated in one direction about its axis by a drive mechanism. Partitions axially spaced from each other in the cavity bound an axial row of compartments in the cavity and are substantially perpendicular to the axis of rotation. A free-flowing, granular, solid material is fed to one of the axially terminal compartments of the row and is discharged from the other axially terminal compartment. The fluid is introduced into the cavity by a supply system and released from the cavity after interacting with the solid.

Channels connect the compartments in axial sequence and are located outside the drum cavity. Each channel connects two axially consecutive compartments through respective apertures in the drum which are offset from each other axially and circumferentially. A first one of the two apertures which is axially nearer the end of the drum to which the solid material is being fed than the second aperture leads the second aperture circumferentially during rotation of the drum.

Other features, additional objects, and many of the attendant advantages of this invention will readily be appreciated as the same becomes better understood from the following detailed description of a preferred embodiment and of a modification thereof when considered in connection with the appended drawing in which: I

FIG. 1 shows apparatus of the invention in sideelevational section on the axis of drum rotation;

FIG. 2 shows a portion of the apparatus of FIG. 1 in plan section through the axis of rotation;

FIG. 3 is a front elevational section of the apparatus of FIG. 1 taken on the line III--III in FIG. 2;

FIG. 4 is a fragmentary section of the apparatus on line IVIV in FIG. 2; and

FIG. 5 shows a modification of the apparatus of FIGS. 1 to 4 in a fragmentary view similar to that of FIG. 2.

Referring now to the drawing in detail, and initially to FIG. 1, there is shown a drum 10 whose cylindrical, circumferential wall 1 rests on rollers 11, 12 which are driven in a conventional manner by respective shafts ll, 12. The cavity bounded by the wall 1 is axially closed by stationary covers 2,3. A tubular support 14 is fixedly sealed in the cover 2 and is coaxial with the drum wall 1. Tubular nozzles 13 communicating with the interior of the support 14 are fixedly attached to the support 14 and have open orifices near the inner face of the wall 1.

The cavity of the drum 10 is axially divided into five compartments l9 23 by four flat, annular partitions 15 18 whose circumferences are fastened to the wall 1 in sealing engagement. The support 14 passes with ample clearance through the central openings of the partitions, and thus extends through the entire row of compartments, a pair of nozzles 13 being arranged in each compartment.

The axially terminal compartments 19,23 of the row are axially wider than the central compartments 15,16, 17, and their pairs of nozzles are spaced from the covers 2,3 which bound the compartments. A stationary feed pipe 24 leads from an overhead bin (not shown) through the cover 2 into the axial portion of the compartment 19 which is free from nozzles 13, and a discharge chute or spout 27'leads from the portion of the compartment 23 free from nozzles outward through the cover 3. Baffles 25,28 in the portions of the compartments 19,23 adjacent the covers 2,3 tend to move the granular material axially toward the discharge chute 27.

A housing 26, presently to be described in more detail, is attached to the outer face of the wall 1 and is statically balanced relative to the axis of rotation by a diametrically opposite counterweight 30 on the outer wall face. A fluid admitted to the cavity of the drum 10 through the support 14 and the nozzles 13 is released through a tubular port 29 arranged near the top of the stationary cover 3. Ribs 43,44 only partly illustrated, project from the inner face of the wall 1 a radial distance smaller than the spacing of the nozzle orifices from the drum wall 1 so that the nozzles 13 clear the ribs 43,44 during rotation of the wall 1.

In FIG. 2, the three identical central compartments 20,21, 22 and identical elements associated therewith are represented by a single compartment 20' and associated elements, and the sectional view of FIG. 4 will be understood to be representative of corresponding views taken through each of the compartments 20,21, or 22.

The wall I has a rectangular and almost square aperture 39 whose pairs of sides are respectively parallel to the adjacent partition 15 and to the axis of drum rotation. Ap'ertures 40, substantially identical with the aperture 39, extend axially in each of the central compartments 30', that is, the compartments 20,21, and 22, from one of the axially bounding partitions to the other, and the four apertures 39,40 which are axially aligned in the wall 1 lead from the drum cavity into the housing 26.

wall 1, another longitudinal wall 32 perpendicular to the wall 31 and spaced from the wall 1 in a radially outward direction, and a third longitudinal wall 33 which slopes obliquely from the wall 32 toward the outer face of the wall 1. Dividing walls 36,37,38 in housing 26 between the wall 1 and the walls 32,33 are helically curved and bound channels 34,35 which lead from each aperture 39,40 to the axially adjacent compart ment in planes inclined obliquely relative to the axis of rotation of the drum at an angle of 45. Each channel 34,35 terminates at another aperture 41,42 in the wall 1 which has an approximately rhombic shape, two sides of the rhombus being parallel and closely adjacent the partitions bounding the compartment into which the aperture 41,42 leads from the corresponding channel 34, 35, and the two other parallel sides being parallel to the afore-mentioned obliquely inclined planes.

Each channel 34,35 thus leads from one compartment to the axially adjacent compartment nearer the discharge chute 27, the arrangement being such that the apertures 39,40 are axially and circumferentially offset from the apertures 41,42 at the ends of the same channel, the apertures 39,40 being axially nearer the feed pipe 24 and leading the apertures 41,42 circumferentially during the normal rotation of the drum 10 in a counterclockwise direction, as indicated by a curved arrow in FIGS. 3 and 4.

During operation of the apparatus, enough of the treated, free-flowing, granular material 4, such as green coffee beans is admitted continuously or intermittently to the drum 10 to keep the orifices of the nozzles 13 embedded in the material which is lifted by frictional engagement with the rotating wall 1 to a height determined by its angle of repose. The coffee beans are fed to that portion of the compartment 19 which is free from nozzles 13, and is gradually shifted to the portion of the compartment 19 nearer the partition 15 by the baffle 25 attached to the wall 1 so that the beans are exposed to hot air discharged from the nozzles 13, and moisture is expelled from the beans while they perform a tumbling movement. Beans are lifted by friction in a circular arc with the wall 1, and then slide down along the chord of the arc thereafter to resume their arcuate movement. The formation of a stagnant center, sometimes observed in particulate material tumbling in a rotating drum, is prevented by the vigorous stream of air discharged from the nozzle 13 which are obliquely inclined, as is seen in FIG. 3, to locate their orifices near the center of the tumbling mass.

When the aperture 39 in the compartment 19 is aligned with the beans 4 which occupy only a small part of the compartment, a portion of the beans present drops into the channel 34, as is seen in FIG. 3, and is discharged from the channel into the compartment 20 through the aperture 41 during continued rotation of the drum, as is best seen in FIG. 4. The average dwell time of the beans 4 in each compartment of the drum 10 thus is a constant multiple of one revolution of the drum l0, and the beans are so intimately mixed by the rotating drum l0 and the gas emitted from the nozzles 13 that they are ultimately discharged from the chute 27 in uniformly roasted condition.

The channels 34,35 are entirely located outside the cavity of the drum 10, and thus do not interfere with the tumbling of the beans. The gas discharged from the nozzles, after having interacted with the beans, passes through the central apertures of the partitions 15 to 18, and is ultimately released from the port 29 carrying with it water vapor and other volatilized ingredients of the green coffee beans.

The ribs 43,44 assist in lifting the beans and prevent their sliding down along the surface of the wall 1, particularly after they have lost their moisture, and their angle of repose has been reduced.

Modifications of the apparatus described above will readily suggest themselves to those skilled in the art. The arrangement of the channels 34,35 in a common housing 26 greatly reduces the first cost of the apparatus, but makes a counterweight30 desirable. If more convenient, the several channels may be spaced angularly about the axis of rotation so as to balance the drum and to make a counterweight unnecessary. More than one channel may be provided to connect axially consecutive compartments. Channels inclined at an angle of 45, such as the channels 34,35, combine adequate flow section, short overall length, and a minimal space requirement in a most advantageous manner, but other arrangements may be chosen under suitable specific conditions.

The amount of coffee beans transferred from one compartment to the next is determined, under otherwise identical conditions, by the size of the apertures 39,40, whereas the size of the apertures 41,42 merely determines the rate at which the transferred beans enter the next compartment, and smaller discharge apertures permit the channels to be shortened.

A modification of this kind is seen in FIG. 5 which illustrates apparatus of the invention identical with that of FIGS. 1 to 4.as far as not specifically shown and described otherwise. Only the first two compartments 191, 201 circumferentially bounded by the drum wall 1' and axially bounded by partitions 151,161 are seen, the other compartments being analogous. The housing 261 which encloses the channels 341,351 is U-shaped in cross section and provided with oblique walls 361,371,381 between the channels. Each channel extends from a rectangular aperture 391,401,,not significantly different from the apertures 39,40 to an aperture 41 1, 421 in the axially consecutive compartment which has the shape of a right, isoceles triangle. One of the legs of the triangle is parallel and closely adjacent the partition which separates the two compartments connected by the channel. The other leg is parallel to the axis of rotation. In its mode of operation, the apparatus of FIG. 5 differs from that of FIGS. 1 to 4 by the slower discharge of the beans from the channels 341,351. Structurally, it is distinguished by a housing 261 whose circumferential dimensions are significantly smaller than those of the housing 26. Both housings are coextensive axially with all compartments of the associated drums. i

It will be appreciated that the drums of the invention are normally provided with external lagging for thermal insulation if used for roasting coffee, and may be provided with heating elements on the external face of the wall 1 to supplement the effect of the hot air discharged from the nozzles 13, and such external heating may make the nozzles 13 unnecessary.

The provision of axial portions free from nozzles 13 in the compartments 19,23 greatly enhances the effectiveness of the apparatus by extending the dwell time in theaxially terminal compartments and preventing premature discharge through the aperture 39 of the discharge chute 27. Axial movement of the treated material within the axially terminal compartments is brought about by the baffles 25,28.

The apparatus illustrated has been found effective for roasting coffee, cocoa, or malt. It may be adapted for other applications so that the dwell times in the individual compartments are different by merely varying the axial spacing of the partitions or the effective flow sections of the connecting channels. Obviously, individual supply ducts in the support 14 may be connected with the nozzles 13 in the several compartments. for feeding to each compartment of fluid of different temperature or composition. If the angle of repose of the treated material is changed by the treatment, the angular posi tions of the nozzles 13 may be varied accordingly in the individual compartments, the angular positions of all nozzles may be changed simultaneously to adapt the apparatus to a different application by turning the support 14 in the cover 3, and it may be advantageous to oscillate the support 14 angularly together with the nozzles 13 through a small acute angle for a further intensification of the agitating effect produced by the discharged gas stream.

lt should be understood, therefore, that the foregoing disclosure relates only to preferred embodiments of the invention, and that it is intended to cover all changes and modifications of the examples of the invention herein chosen for the purpose of the disclosure which do not constitute departures from the spirit and scope of the invention set forth in the appended claims.

What is claimed is:

1. Apparatus for contacting a free-flowing particulate solid with a fluid comprising, in combination:

a. a drum member having a horizontally extending axis and-enclosing a cavity;

b. drive means for rotating said drum member about said axis in a predetermined direction;

c. a plurality of partitions axially spaced from each other in said cavity,

1. said partitions axially bounding anaxial row of compartments in said cavity and being substantially perpendicular to said axis;

d. feeding means for feeding a free-flowing, granular,

solid material to one of the axially terminal compartments of said row;

e. discharge means for discharging said material from the other axially terminal compartment;

f. fluid supply means for supplying a fluid to said cavity for interaction with said material;

g. releasing means for releasing said fluid from said cavity separately from said material;

h. a plurality of channels connecting said compartments in axial sequence,

1. each channel being located outside said cavity and connecting two axially consecutive compartments through two respective apertures in said drum member,

2. said apertures being axially and circumferentially offset from each other,

3. a first one of said two apertures being axially nearer said one axially terminal compartment than the second aperture and circumferentially leading said second aperture during said rotating of the drum member.

2. Apparatus as set forth in claim 1, wherein said fluid supply means include a stationary support, and a plurality of nozzles having respective discharge orifices in said compartments radially adjacent said drum member.

3. Apparatus as set forth in claim 2, further comprising a housing mounted on said drum member outside said cavity, said housing being axially substantially coextensive with said compartments, and wall means in said housing defining said plurality of channels.

4. Apparatus as set forth in claim 3, wherein said first aperture associated with one of said channels is substantially rectangular and extends axially from one to the other of the two partitions bounding the compartment connected by said rectangular aperture to said one channel.

5. Apparatus as set forth in claim 3, said channels extending in respective planes intersecting said axis at an angle of approximately 45.

6. Apparatus as set forth in claim 5, wherein said second aperture associated with one of said channels is of substantially rhombic shape, two of the parallel sides of said shape being located closely adjacent respective partitions axially bounding the compartment connected by said rhombic aperture to said one channel, the other two parallel sides of said shape being parallel to said intersecting planes.

7. Apparatus as set forth in claim 5, wherein said second aperture associated with one of said channels has the approximate shape of a right, isoceles triangle, one of the legs of said triangle being parallel to and closely adjacent the partition bounding the compartment connected by said triangular aperture to said one channel in a direction toward said one axially terminal compartment, the other leg being parallel to said axis.

8. Apparatus as set forth in claim 3, further comprising counterweight means on said drum diametrically opposite said housing for locating the center of gravity of said drum, and of said channels, closely adjacent said axis.

9. Apparatus as set forth in claim 2, further comprising baffle means mounted on said drum member in said cavity for lifting said granular material during said rotating of the drum member, said baffie means including a plurality of rib members projecting from said drum member a distance smaller than the spacing of said discharge orifices from said drum member.

10. Apparatus as set forth in claim 2, wherein at least one of said-axially terminal compartments has an axial portion adjacent the other axially terminal compartment and an axial portion remote from said other axi ally terminal compartment, said axial portions freely communicating with each other, one of said nozzles being located in said adjacent axial portion, the remote portion being free of nozzles, and a baffle means in said remote portion for axially shifting said granular material from said remote portion toward said discharge means during said rotation of the drum member.

t I i I! t 

2. Apparatus as set forth in claim 1, wherein said fluid supply means include a stationary support, and a plurality of nozzles having respective discharge orifices in said compartments radially adjacent said drum member.
 2. said apertures being axially and circumferentially offset from each other,
 3. a first one of said two apertures being axially nearer said one axially terminal compartment than the second aperture and circumferentially leading said second aperture during said rotating of the drum member.
 3. Apparatus as set forth in claim 2, further comprising a housing mounted on said drum member outside said cavity, said housing being axially substantially coextensive with said compartments, and wall means in said housing defining said plurality of channels.
 4. Apparatus as set forth in claim 3, wherein said first aperture associated with one of said channels is substantially rectangular and extends axially from one to the other of the two partitions bounding the compartment connected by said rectangular aperture to said one channel.
 5. Apparatus as set forth in claim 3, said channels extending in respective planes intersecting said axis at an angle of approximately 45*.
 6. Apparatus as set forth in claim 5, wherein said second aperture associated with one of said channels is of substantially rhombic shape, two of the parallel sides of said shape being located closely adjacent respective partitions axially bounding the compartment connected by said rhombic aperture to said one channel, the other two parallel sides of said shape being parallel to said intersecting planes.
 7. Apparatus as set forth in claim 5, wherein said second aperture associated with one of said channels has the approximate shape of a right, isoceles triangle, one of the legs of said triangle being parallel to and closely adjacent the partition bounding the compartment connected by said triangular aperture to said one channel in a direction toward said one axially terminal compartment, the other leg being parallel to said axis.
 8. Apparatus as set forth in claim 3, further comprising counterweight means on said drum diametrically opposite said housing for locating the center of gRavity of said drum, and of said channels, closely adjacent said axis.
 9. Apparatus as set forth in claim 2, further comprising baffle means mounted on said drum member in said cavity for lifting said granular material during said rotating of the drum member, said baffle means including a plurality of rib members projecting from said drum member a distance smaller than the spacing of said discharge orifices from said drum member.
 10. Apparatus as set forth in claim 2, wherein at least one of said axially terminal compartments has an axial portion adjacent the other axially terminal compartment and an axial portion remote from said other axially terminal compartment, said axial portions freely communicating with each other, one of said nozzles being located in said adjacent axial portion, the remote portion being free of nozzles, and a baffle means in said remote portion for axially shifting said granular material from said remote portion toward said discharge means during said rotation of the drum member. 